00:01
Let me take note what's given here.
00:03
So the sample mean denoted by x bar, that was given as 21.
00:07
And the sample standard division, this is 5 .8.
00:10
And the sample size, which is 23.
00:13
And the confidence level, so the confidence level, which is given as 80 percent.
00:18
So first of all, let me start with what assumptions need to be made about this population.
00:23
So when we look at the given standard division, which is for the sample standard division, we don't know the population standard division.
00:30
So because of that, the population follows the student t distribution.
00:33
So for the choice question, we are going to just use the t distribution.
00:40
This is the correct answer for the choices.
00:43
Let's get the confidence interval.
00:44
So the confidence interval for mean, which is the x bar, this is plus one minus t alpha over two times sample standard division, and divided by square root of the sample size.
00:55
Let's get the alpha value, which is one minus confidence level.
01:00
We need the alpha over two, which is one minus 0 .88, divided by two.
01:04
This is 0 .1 here.
01:05
And the degree of freedom, this is n minus one...